Obstructive Sleep Apnea (OSA) is the recurrent occlusion of the upper airways during sleep due to the decreased neuromuscular tone in the tongue and the pharyngeal muscles. A 1993 study in Wisconsin has shown that 2 to 4 percent of the population is affected. This number reaches 9 percent in another study conducted in Australia. This is clearly a serious problem which affects a large segment of the population and can lead to severe disorders such as stroke. The current methods used to treat this sleep disorder provide only partial solutions and only in a limited number of cases. We propose to develop a closed-loop control nerve prosthetic device as a treatment for OSA to be tested in a dog model. The hypoglossal nerve innervates the genioglossus, the muscle mainly responsible for protrusion of the tongue. The spontaneous activity of the hypoglossal nerve will be recorded during normal sleeping conditions and used as the feedback signal to trigger the stimulation of the genioglossus. Electrical stimulation will be delivered to the hypoglossal nerve with the same electrode used for recording and will be synchronized with inspirations to keep the airways open. Electrical stimulation of this nerve has already been proposed and tested experimentally by other groups. The innovative part of this project is to use the stimulating electrode to record the nerve activity in order to detect the occlusion and trigger the stimulation. This project has an element of risk because chronic recording of hypoglossal nerve activity in a non-anesthetized animal has never been reported as well as the design of a neural prosthetic system capable of recording and stimulation with the same electrode. Successful completion of this project could lead to the design of a neuronal prosthesis capable of restoring a normal pattern of breathing without causing arousal from sleep in humans.